from PyQt5.QtWidgets import QDialog, QVBoxLayout, QComboBox, QPushButton

class FormatConverter(QDialog):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setWindowTitle("格式转换")
        self.setFixedSize(300, 150)
        layout = QVBoxLayout()
        self.format_box = QComboBox()
        self.format_box.addItems(["PDF", "DOCX", "PPTX", "TXT"])
        layout.addWidget(self.format_box)
        QPushButton("开始转换", clicked=self.accept).addTo(layout)
        self.setLayout(layout)